CN102899559A - Preparation method of steel for oil delivery pipeline - Google Patents

Abstract

A preparation method of steel for an oil delivery pipeline belongs to the field of the steel industry. The invention aims to provide the preparation method of the steel for the oil delivery pipeline through redesigning components and increasing a steel charging mode of a heating furnace in a slab hot charging process. The technological process provided by the invention is as follows: pouring melted iron into a tank, preprocessing through desulfuration, smelting through a converter, argon blowing, refining for deep desulfurization and calcium treatment through an LF (low frequency) furnace, continuous casting, hot charging slabs under the temperature of not less than 400 DEG C, heating through a heating furnace, roughing and descaling, roughing and returning for five passes, cropping heads and tails, precisely rolling for 6 passes, laminar cooling, coiling, sampling for inspection, and releasing for delivering goods. The preparation method of the steel for the oil delivery pipeline steel, provided by the invention, is more beneficial for the industries to reduce the production cost and suitable for the mass production of the factories, simultaneously guarantees the quality of the final products, and ensures the optimal production cost, so that factory benefit is maximized.

Description

The preparation method of petroleum conveying pipeline steel

Technical field

The invention belongs to the Steel industry field.

Background technology

The exploitation of the effective hot-rolled coil of petroleum transport, this coil of strip product in use except requiring to have the higher compressive strength, also require to have higher low-temperature flexibility and good welding property.The present invention is mainly used in solving and improves transfer lime with the hot-rolled coil performance index and production process is controlled easily.Along with continually developing of oil and gas and other energy, use pipeline to carry the oil gas equal energy source, have more economy, safety, efficient advantage, but long-distance transport pipe environment for use is complicated, and be subjected to the impact of the factors such as medium, temperature, safety, require pipe line steel to have high strength, high tenacity, good weldability and solidity to corrosion etc.

Summary of the invention

The objective of the invention is to re-start Composition Design, and the steel slab operation increases the preparation method of the petroleum conveying pipeline steel of process furnace dress punching block formula.

Technological process of the present invention is: and the molten iron ladle pouring → desulfurization pre-treatment → converter smelting → Argon → dark desulfurization of LF stove refining, calcium processing → continuous casting → steel slab 〉=400 ℃ → process furnace heating → roughing de-scaling → roughing comes and goes five passages → crop, back-end crop → finish rolling 6 passages → laminar flow cools off → batches → and inspection by sampling → clearances deliver;

The composition of pipe line steel such as following table:

Hot metal pretreatment: molten iron carries out desulfurization to be processed, and enters stove molten iron [S]≤0.005%, scratches clean desulfurization slag after the desulfurization, guarantees to reveal bright more than 90%;

Converter smelting:

1. adopt self-produced steel scrap, drying, steel scrap meets steel scrap standard and [S]≤0.030%, does not allow to use pig;

2. tapping adds top slag lime 500Kg, aluminum shot 10Kg, tapping time 〉=5 minute, and clean, red packet tapping, pushing off the slag during tapping, thickness of slag layer is controlled in the 70mm, and the bottom blowing pattern adopts omnidistance Argon pattern;

Argon control: must open argon gas before the tapping, tapping does not allow to close argon gas midway to the omnidistance Argon of departures, meets Special Circumstances and turns argon pressure down; Arrive at a station thermometric, decide oxygen, feed the aluminum steel deoxidation to free oxygen less than 10ppm, add ferro-niobium, then soft blow was taken a sample after 2 minutes;

The LF refining furnace:

According to target composition requires to carry out trimming, and LF is adding ferrotianium behind the intensificationization slag for the first time, makes white slag and carries out the desulfurization processing, and desulfurization is to S≤0.005%;

The alloying constituent adjustment finishes to feed the operation of Si-Ca line before the departures, and the line feeding amount is greater than 500m, and wire-feeding velocity guarantees that greater than 5.0m/s the calcium aluminum ratio is not less than 0.1 in the steel;

Silicon-calcium wire feeds that silk is complete to carry out soft blow, and molten steel soft blow time 〉=7min takes a sample before molten steel is leaving from station;

Continuous casting:

I, the casting of employing whole process protection, long nozzle adds packing ring and Ar envelope, and large bag is added a cover;

II, liquidus temperature TL=1520 ℃, the bag temperature range is 1535～1545 ℃ in the target;

III, middle bag use magnesia material; It is stable that mold liquid level keeps, and prevents that secondary oxidation of steel, suction nitrogen and covering slag are involved in;

IV, crystallizer protecting residue adopt pipe line steel mould flux, conical degree of crystallizer: 1%.

The present invention more is conducive to factory and reduces production costs, and when adapting to factory's scale operation, guarantees final quality in kind, guarantees that production cost is optimum, makes factory's maximizing the benefits.

Description of drawings

Fig. 1 is X52 tapping temperature histogram of the present invention (normal state).

Embodiment

The objective of the invention is to re-start Composition Design, and the steel slab operation increases the preparation method of the petroleum conveying pipeline steel of process furnace dress punching block formula.

Technological process of the present invention is: and the molten iron ladle pouring → desulfurization pre-treatment → converter smelting → Argon → dark desulfurization of LF stove refining, calcium processing → continuous casting → steel slab 〉=400 ℃ → process furnace heating → roughing de-scaling → roughing comes and goes five passages → crop, back-end crop → finish rolling 6 passages → laminar flow cools off → batches → and inspection by sampling → clearances deliver;

The composition of pipe line steel such as following table:

Hot metal pretreatment: molten iron carries out desulfurization to be processed, and enters stove molten iron [S]≤0.005%, scratches clean desulfurization slag after the desulfurization, guarantees to reveal bright more than 90%;

Converter smelting:

1. adopt self-produced steel scrap, drying, steel scrap meets steel scrap standard and [S]≤0.030%, does not allow to use pig;

2. tapping adds top slag lime 500Kg, aluminum shot 10Kg, tapping time 〉=5 minute, and clean, red packet tapping, pushing off the slag during tapping, thickness of slag layer is controlled in the 70mm, and the bottom blowing pattern adopts omnidistance Argon pattern;

Argon control: must open argon gas before the tapping, tapping does not allow to close argon gas midway to the omnidistance Argon of departures, meets Special Circumstances and turns argon pressure down; Arrive at a station thermometric, decide oxygen, feed the aluminum steel deoxidation to free oxygen less than 10ppm, add ferro-niobium, then soft blow was taken a sample after 2 minutes;

The LF refining furnace:

According to target composition requires to carry out trimming, and LF is adding ferrotianium behind the intensificationization slag for the first time, makes white slag and carries out the desulfurization processing, and desulfurization is to S≤0.005%;

The alloying constituent adjustment finishes to feed the operation of Si-Ca line before the departures, and the line feeding amount is greater than 500m, and wire-feeding velocity guarantees that greater than 5.0m/s the calcium aluminum ratio is not less than 0.1 in the steel;

Silicon-calcium wire feeds that silk is complete to carry out soft blow, and molten steel soft blow time 〉=7min takes a sample before molten steel is leaving from station;

Continuous casting:

I, the casting of employing whole process protection, long nozzle adds packing ring and Ar envelope, and large bag is added a cover;

II, liquidus temperature TL=1520 ℃, the bag temperature range is 1535～1545 ℃ in the target;

III, middle bag use magnesia material; It is stable that mold liquid level keeps, and prevents that secondary oxidation of steel, suction nitrogen and covering slag are involved in;

IV, crystallizer protecting residue adopt pipe line steel mould flux, conical degree of crystallizer: 1%.

The water yield is carried out with reference to following table:

The copper coin position	Narrow limit, left side copper coin	Narrow limit, right side copper coin	The inner arc side copper plate	The outer arc side copper plate
					Flow setting value (l/min)	390	390	3120	3120

Target casting speed m/min according to the form below is carried out, and waters steel by constant pulling rate in the production as far as possible:

Middle bag waters time crop, back-end crop length is 1000mm, and guarantees that the central pipe removal is clean.

Hot and cold dress contrast:

The slab cold charge

Heat-up time min

Tapping temperature ℃

Roughing temperature out ℃

Finish rolling temperature out ℃

Coiling temperature ℃

Furnace pressure pa

The cold pattern of layer

≥180

1220±20

1090±20

860±20

610±20

5-15

The leading portion cooling

Steel slab

Heat-up time min

Tapping temperature ℃

Roughing temperature out ℃

Finish rolling temperature out ℃

Coiling temperature ℃

Furnace pressure pa

The cold pattern of layer

≥160

1220±20

1090±20

840±20

590±20

5-15

The leading portion cooling

Safeguard measure:

Heating

Slab is checked

The slab material loading is single by the production scheduling plan that the material loading operator issues according to production department, and slab number, slab specification and weight are checked.

Require: the temperature difference in the slab table≤20 ℃; The temperature difference between stove≤15 ℃;

The control temperature is returned in roughing: 1070 ℃;

Roughing

Roughing de-scaling system

O: come into operation *: do not come into operation

Workpiece thickness control

Finish rolling

Coil Box

Adopt Coil Box to batch or direct mode operation (pressing workpiece thickness divides).

The flying shear system:

All the band steel all needs crop;

The finish rolling de-scaling comes into operation

Precision rolling working roll water coolant, water in dust removal, with the flow of steel water coolant, side spray water

Get rid of the rolling rule of frame

Rolling less than not allowing to get rid of frame in 6.0 the belt steel rolling process;

6.0-10.0 can get rid of 1 frame, can not get rid of F1 and F6.

The present invention has adopted assurance heat-up time that (actual average heat-up time 〉=190min) and tapping temperature (seeing attached 1) guarantee that the microalloy element solutes such as Nb, Ti dissolve in the austenite fully and guarantee and obtain less original austenite grains size, play crystal grain thinning and put forward high-intensity purpose.

By control roughing temperature out, control finishing temperature, improve the compression ratio of finishing stand by improving workpiece thickness, adopt the controlled rolling in austenite non-recrystallization district, thereby obtain more tiny ferrite crystal grain, formulate finishing temperature and be controlled at 820 ℃ ~ 860 ℃.The cooling control strategy of Nb microalloying steel grade should be roll rear usefulness faster speed of cooling enter ferrite forming core temperature range, be conducive to so abundant refinement ferrite crystal grain, follow-uply want suitable slow cooling be beneficial to the ferrite crystal grain homogenizing, curling temperature will suit, and avoids producing Widmannstatten structure.Therefore adopt the leading portion cooling, curling Temperature Setting is 570 ℃ ~ 610 ℃.

Actual process control and product performance contrast are as follows:

Find out that from upper table behind slab cold charge and the hot charging, by the controlled rolling temperature, resulting product intensity and toughness do not have difference, performance all can reach customer requirement.

The process furnace energy consumption comparison is as follows:

Process furnace productivity and iron scale burn out rate are as follows:

Time	Charging mode	Oxidization burning loss rate %	Gas consumption amount m3/t
				2012.4-2012.7	Hot charging	2.5%	170
2012.4-2012.7	Cold charge	2.2%	167

By hot charging and cold charge contrast statistics, iron scale burn out rate and coal gas energy consumption significantly descend, and have outstanding meaning for enterprise's cost efficiency in present steel market and pessimistic situation.

Claims (1)

1. the preparation method of a petroleum conveying pipeline steel, it is characterized in that: its technological process is: and the molten iron ladle pouring → desulfurization pre-treatment → converter smelting → Argon → dark desulfurization of LF stove refining, calcium processing → continuous casting → steel slab 〉=400 ℃ → process furnace heating → roughing de-scaling → roughing comes and goes five passages → crop, back-end crop → finish rolling 6 passages → laminar flow cools off → batches → and inspection by sampling → clearances deliver;

The composition of pipe line steel such as following table:

Hot metal pretreatment: molten iron carries out desulfurization to be processed, and enters stove molten iron [S]≤0.005%, scratches clean desulfurization slag after the desulfurization, guarantees to reveal bright more than 90%;

Converter smelting:

1. adopt self-produced steel scrap, drying, steel scrap meets steel scrap standard and [S]≤0.030%, does not allow to use pig;

2. tapping adds top slag lime 500Kg, aluminum shot 10Kg, tapping time 〉=5 minute, and clean, red packet tapping, pushing off the slag during tapping, thickness of slag layer is controlled in the 70mm, and the bottom blowing pattern adopts omnidistance Argon pattern;

Argon control: must open argon gas before the tapping, tapping does not allow to close argon gas midway to the omnidistance Argon of departures, meets Special Circumstances and turns argon pressure down; Arrive at a station thermometric, decide oxygen, feed the aluminum steel deoxidation to free oxygen less than 10ppm, add ferro-niobium, then soft blow was taken a sample after 2 minutes;

The LF refining furnace:

According to target composition requires to carry out trimming, and LF is adding ferrotianium behind the intensificationization slag for the first time, makes white slag and carries out the desulfurization processing, and desulfurization is to S≤0.005%;

The alloying constituent adjustment finishes to feed the operation of Si-Ca line before the departures, and the line feeding amount is greater than 500m, and wire-feeding velocity guarantees that greater than 5.0m/s the calcium aluminum ratio is not less than 0.1 in the steel;

Silicon-calcium wire feeds that silk is complete to carry out soft blow, and molten steel soft blow time 〉=7min takes a sample before molten steel is leaving from station;

Continuous casting:

I, the casting of employing whole process protection, long nozzle adds packing ring and Ar envelope, and large bag is added a cover;

II, liquidus temperature TL=1520 ℃, the bag temperature range is 1535～1545 ℃ in the target;

III, middle bag use magnesia material; It is stable that mold liquid level keeps, and prevents that secondary oxidation of steel, suction nitrogen and covering slag are involved in;

IV, crystallizer protecting residue adopt pipe line steel mould flux, conical degree of crystallizer: 1%.

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